Respuestas comparativas de la densidad de siembra y el uso de herbicidas en el control de malezas en trigo (Triticum aestivum L.) cv. Chasicó INTA

Se comparó la respuesta del trigo cv. Chasicó 1NTA sembrado a tres densidades (200, 250 Y 300 pl/m2) con y sin competencia de malezas frente a la aplicación de cuatro herbicidas (Bromoxinil 2.4-D. picloram + 2,4-D y Dicamba + 2,4 D) en dos estadios (2-4 macollos y detección. del primer nudo) La densidad de siembra no produjo efecto significativo (p=0.05) sobre la interferencia de malezas. Estas produjeron mermas de rendimiento de alrededor de 50%. Los herbicidas aplicados en la segunda epoca, en especial picloram + 2.4-D y Dicamba + 2.4-D, resultaron fitotóxicos y produjeron rendimientos similares a los tratamientos enmalezados. El Bromoxinil aplicado en 2-4 macollos fue el producto de mejor comportamiento. El 2,4-D produjo resultados intermedios entre las mezclas y el Bromoxinil. El componente de rendimiento que más afectaron los herbicidas fue granos por espigas. Los tratamientos desmalezados superaron a las aplicaciones de herbicidas y Estas a los enmalezados. La ausencia de significancia de la interacción de densidad x desmalezado no permitió comprobar que las densidades de siembra puedan constituirse en un método de control de malezas.Directores: Ings. Agrs. O. J. Rubiolo y F. D. Garcí

CFD Modeling of a Laboratory-Scale Setup for Thermochemical Materials Performance Analysis

The search for energy saving is nowadays mandatory because of the constant growth of CO2 emissions caused by an inefficient energy management. Thermal Energy Storage (TES) has an important role in designing of energy efficient systems, including solar energy storage (daily or seasonal) and waste heat from industrial batch processes. Different solutions are possible for thermal storage, based on sensible heat (e.g. water tanks), latent heat (phase change materials) or reaction enthalpy (thermochemical systems). In Thermochemical TES, a material is chosen so that it shows a high-enthalpy reversible chemical reaction at a desired temperature. In particular, water sorption in some inorganic salt hydrates is pointed out as one of the most suitable reactions for low temperature energy storage (60-120 °C). The reaction products, water and salt in a less hydrated form, are kept separated and consequently the heat is stored. Energy release is obtained with salt hydration. The main advantages are an energy storage capacity higher than other TES technologies and the possibility to control the energy release. On the other hand, one of the main issues is the difficulty to test materials performance, because standard characterization techniques use small amount of samples and their properties change dramatically when the system is scaled up to large reactors. The aim of this work is to realize a laboratory scale setup to test the performance of salt hydrate composites. A scheme of the system is reported in the attached figure (above). The active material is kept in an evaporator at a temperature sufficient to generate the dehydration reaction. Extracted water mass is measured in time in a condenser at 0°C. Air flow, temperature and humidity are measured with sensors in the system. The system was simulated using COMSOL® software. In particular the simulation was inspired by two models from the Application Library, Degradation of DNA in Plasma and Protein Adsorption. At first, a zero dimensional component was created with the Reaction Engineering module with two reactions to evaluate both the dehydration and condensation steps: H2Ocry->H2Ovap H2Ovap->H2Oliq Where H2Ocry is the crystallization water in the salt hydrate, H2Ovap is the air humidity and H2Oliq is the condensed water. Using a Parameter Estimation module, experimental data about dehydration were imported in the software and used to estimate the reactions kinetics constants. After that, using a Generate Space Dependent Model module we obtained a 3D component with a realistic system geometry (see attached figure below) including the modules Chemistry, Transport of Diluted Species, Surface Reactions, Heat transfer in Fluids and Single Phase Laminar Flow. Rate constants calculated in the zero-dimension model were used as first guess for the 3D model reactions. We verified that the model is able to evaluate temperature, flow and water concentration as well as the evolution of the two reactions in time. We expect that this model will allow us to classify different Thermochemical TES materials about their efficiency in heat and mass exchange, as well as to refine the design of the thermal storage system

Sodium Ascorbate induces apoptosis in neuroblastoma cell lines by interfering with iron uptake

<p>Abstract</p> <p>Background</p> <p>Neuroblastoma (NB) is an extra-cranial solid tumour of childhood. In spite of the good clinical response to first-line therapy, complete eradication of NB cells is rarely achieved. Thus, new therapeutic strategies are needed to eradicate surviving NB cells and prevent relapse. Sodium ascorbate has been recently reported to induce apoptosis of B16 melanoma cells through down-regulation of the transferrin receptor, CD71. Since NB and melanoma share the same embryologic neuroectodermal origin, we used different human NB cell lines to assess whether the same findings occurred.</p> <p>Results</p> <p>We could observe dose- and time-dependent induction of apoptosis in all NB cell lines. Sodium ascorbate decreased the expression of CD71 and caused cell death within 24 h. An increase in the global and specific caspase activity took place, as well as an early loss of the mitochondrial transmembrane potential. Moreover, intracellular iron was significantly decreased after exposure to sodium ascorbate. Apoptotic markers were reverted when the cells were pretreated with the iron donor ferric ammonium citrate (FAC), further confirming that iron depletion is responsible for the ascorbate-induced cell death in NB cells.</p> <p>Conclusion</p> <p>Sodium ascorbate is highly toxic to neuroblastoma cell lines and the specific mechanism of vitamin C-induced apoptosis is due to a perturbation of intracellular iron levels ensuing TfR-downregulation.</p

Improving Mechanical Properties and Reaction to Fire of EVA/LLDPE Blends for Cable Applications with Melamine Triazine and Bentonite Clay

The high flame-retardant loading required for ethylene-vinyl acetate copolymer blends with polyethylene (EVA-PE) employed for insulation and sheathing of electric cables represents a significant limitation in processability and final mechanical properties. In this work, melamine triazine (TRZ) and modified bentonite clay have been investigated in combination with aluminum trihydroxide (ATH) for the production of EVA-PE composites with excellent fire safety and improved mechanical properties. Optimized formulations with only 120 parts per hundred resin (phr) of ATH can achieve self-extinguishing behavior according to the UL94 classification (V0 rating), as well as reduced combustion kinetics and smoke production. Mechanical property evaluation shows reduced stiffness and improved elongation at break with respect to commonly employed EVA-PE/ATH composites. The reduction in filler content also provides improved processability and cost reductions. The results presented here allow for a viable and halogen-free strategy for the preparation of high performing EVA-PE composites

Strong reinforcement effects in 2D cellulose nanofibril-graphene oxide (CNF-GO) nanocomposites due to GO-induced CNF ordering

Nanocomposites from native cellulose with low 2D nanoplatelet content are of interest as sustainable materials combining functional and structural performance. Cellulose nanofibril-graphene oxide (CNF-GO) nanocomposite films are prepared by a physical mixing-drying method, with a focus on low GO content, the use of very large GO platelets (2-45 μm) and nanostructural characterization using synchrotron X-ray source for WAXS and SAXS. These nanocomposites can be used as transparent coatings, strong films or membranes, as gas barriers or in laminated form. CNF nanofibrils with random in-plane orientation, form a continuous non-porous matrix with GO platelets oriented in-plane. GO reinforcement mechanisms in CNF are investigated, and relationships between nanostructure and suspension rheology, mechanical properties, optical transmittance and oxygen barrier properties are investigated as a function of GO content. A much higher modulus reinforcement efficiency is observed than in previous polymer-GO studies. The absolute values for modulus and ultimate strength are as high as 17 GPa and 250 MPa at a GO content as small as 0.07 vol%. The remarkable reinforcement efficiency is due to improved organization of the CNF matrix; and this GO-induced mechanism is of general interest for nanostructural tailoring of CNF-2D nanoplatelet composites

A comparative analysis of nanoparticle adsorption as fire-protection approach for fabrics

The present paper critically analyzes the potential for commercially available nanoparticles for enhancing the flame-retardant properties of synthetic and natural fabrics and their corresponding blends. Each nanoparticle has been applied to the fabric through a finishing-like process (namely impregnation/exhausting or, more simply, nanoparticle adsorption) in aqueous media and the resulting properties of these fabrics have been assessed in terms of combustion behavior by use of a cone calorimeter under a heat flux of 35 kW/m2. The influence of these nanoparticles on the main combustion parameters of polyester, cotton, and some of their blends has been thoroughly discussed. As a result of this discussion, a flame-retardant efficiency ranking of the nanoparticles under review has been established